Posts filed under ‘Desinfection and Sterilization’

Gram-negative prosthetic joint infections: risk factors and outcome of treatment.

Clin Infect Dis. 2009 Oct 1;49(7):1036-43

Hsieh PH, Lee MS, Hsu KY, Chang YH, Shih HN, Ueng SW.

Department of Orthopedic Surgery, Chang Gung Memorial Hospital, No. 5, Fu-Hsing St., 333 Kweishian, Taoyuan, Taiwan.


Little information is available regarding the demographic characteristics and outcomes of patients with prosthetic joint infection (PJI) resulting from gram-negative (GN) organisms, compared with patients with PJI resulting from gram-positive (GP) organisms.


We performed a retrospective cohort analysis of all cases of PJI that were treated at our institution during the period from 2000 through 2006.


GN microorganisms were involved in 53 (15%) of 346 first-time episodes of PJI, and Pseudomonas aeruginosa was the most commonly isolated pathogen (21 [40%] of the 53 episodes). Patients with GN PJI were older (median age, 68 vs. 59 years; P<.001) and developed infection earlier (median joint age, 74 vs. 109 days; P<.001) than those with GP PJI. Of the 53 episodes of GN PJI, 27 (51%) were treated with debridement, 16 (30%) with 2-stage exchange arthroplasty, and 10 (19%) with resection arthroplasty. Treating GN PJI with debridement was associated with a lower 2-year cumulative probability of success than treating GP PJI with debridement (27% vs. 47% of episodes were successfully treated; P=.002); no difference was found when a PJI was treated with 2-stage exchange or resection arthroplasty. A longer duration of symptoms before treatment with debridement was associated with treatment failure for GN PJI, compared with for GP PJI (median duration of symptoms, 11 vs. 5 days; P=.02).


GN PJI represents a substantial proportion of all occurrences of PJI. Debridement alone has a high failure rate and should not be attempted when the duration of symptoms is long. Resection of the prosthesis, with or without subsequent reimplantation, as a result of GN PJI is associated with a favorable outcome rate that is comparable to that associated with PJI due to GP pathogens.


April 7, 2017 at 10:07 pm

Are hospital floors an underappreciated reservoir for transmission of health care-associated pathogens?

American Journal of Infection Control March 1, 2017 V.45 N.3 P.336-338

Abhishek Deshpande, MD, PhD, Jennifer L. Cadnum, BS, Dennis Fertelli, BS, Brett Sitzlar, BS, MPH, Priyaleela Thota, MD, Thriveen S. Mana, MS, MBA, Annette Jencson, MT, CIC, Heba Alhmidi, MD, Sreelatha Koganti, MD, Curtis J. Donskey


  • Patient room floors in 5 hospitals were often contaminated with health care-associated pathogens.
  • It was not uncommon for high-touch objects to be direct contact with the floor.
  • Touching objects on the floor frequently resulted in transfer of pathogens to hands.
  • Floors in hospital rooms could be an underappreciated source for pathogen dissemination.


In a survey of 5 hospitals, we found that floors in patient rooms were frequently contaminated with pathogens and high-touch objects such as blood pressure cuffs and call buttons were often in contact with the floor. Contact with objects on floors frequently resulted in transfer of pathogens to hands.


March 10, 2017 at 7:43 am

Propionibacterium acnes: Disease-Causing Agent or Common Contaminant? Detection in Diverse Patient Samples by Next-Generation Sequencing

Journal of Clinical Microbiology April 2016 V.54 N.4 P.980-987

Sarah Mollerup, Jens Friis-Nielsen, Lasse Vinner, Thomas Arn Hansen, Stine Raith Richter, Helena Fridholm, Jose Alejandro Romero Herrera, Ole Lund, Søren Brunak, Jose M. G. Izarzugaza, Tobias Mourier, Lars Peter Nielsen, and Anders Johannes Hansen

aCentre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Copenhagen, Denmark

bCenter for Biological Sequence Analysis, Department of Systems Biology, Technical University of Denmark, Kongens Lyngby, Denmark

cDisease Systems Biology Program, Panum Institute, University of Copenhagen, Copenhagen, Denmark

dDepartment of Autoimmunology and Biomarkers, Statens Serum Institut, Copenhagen S, and Aalborg University, Health Sciences, Aalborg, Denmark

Propionibacterium acnes is the most abundant bacterium on human skin, particularly in sebaceous areas. P. acnes is suggested to be an opportunistic pathogen involved in the development of diverse medical conditions but is also a proven contaminant of human clinical samples and surgical wounds.

Its significance as a pathogen is consequently a matter of debate. In the present study, we investigated the presence of P. acnes DNA in 250 next-generation sequencing data sets generated from 180 samples of 20 different sample types, mostly of cancerous origin.

The samples were subjected to either microbial enrichment, involving nuclease treatment to reduce the amount of host nucleic acids, or shotgun sequencing. We detected high proportions of P. acnes DNA in enriched samples, particularly skin tissue-derived and other tissue samples, with the levels being higher in enriched samples than in shotgun-sequenced samples.

P. acnes reads were detected in most samples analyzed, though the proportions in most shotgun-sequenced samples were low. Our results show that P. acnes can be detected in practically all sample types when molecular methods, such as next-generation sequencing, are employed.

The possibility of contamination from the patient or other sources, including laboratory reagents or environment, should therefore always be considered carefully when P. acnes is detected in clinical samples.

We advocate that detection of P. acnes always be accompanied by experiments validating the association between this bacterium and any clinical condition.


March 9, 2017 at 3:35 pm

Pneumococcal Colonization Rates in Patients Admitted to a United Kingdom Hospital with Lower Respiratory Tract Infection: a Prospective Case-Control Study

Journal of Clinical Microbiology April 2016 V.54 N.4 P.944-949

Andrea M. Collins, Catherine M. K. Johnstone, Jenna F. Gritzfeld, Antonia Banyard, Carole A. Hancock, Angela D. Wright, Laura Macfarlane, Daniela M. Ferreira, and Stephen B. Gordon

aRespiratory Infection Group, Royal Liverpool and Broadgreen University Hospital Trust, Liverpool, United Kingdom

bRespiratory Infection Group, Liverpool School of Tropical Medicine, Liverpool, United Kingdom

cLocal Comprehensive Research Network, Liverpool, United Kingdom

Current diagnostic tests are ineffective for identifying the etiological pathogen in hospitalized adults with lower respiratory tract infections (LRTIs). The association of pneumococcal colonization with disease has been suggested as a means to increase the diagnostic precision. We compared the pneumococcal colonization rates and the densities of nasal pneumococcal colonization by (i) classical culture and (ii) quantitative real-time PCR (qPCR) targeting lytA in patients with LRTIs admitted to a hospital in the United Kingdom and control patients. A total of 826 patients were screened for inclusion in this prospective case-control study. Of these, 38 patients were recruited, 19 with confirmed LRTIs and 19 controls with other diagnoses. Nasal wash (NW) samples were collected at the time of recruitment. Pneumococcal colonization was detected in 1 patient with LRTI and 3 controls (P = 0.6) by classical culture. By qPCR, pneumococcal colonization was detected in 10 LRTI patients and 8 controls (P = 0.5). Antibiotic usage prior to sampling was significantly higher in the LRTI group than in the control group (19 versus 3; P < 0.001). With a clinically relevant cutoff of >8,000 copies/ml on qPCR, pneumococcal colonization was found in 3 LRTI patients and 4 controls (P > 0.05). We conclude that neither the prevalence nor the density of nasal pneumococcal colonization (by culture and qPCR) can be used as a method of microbiological diagnosis in hospitalized adults with LRTI in the United Kingdom. A community-based study recruiting patients prior to antibiotic therapy may be a useful future step.


March 9, 2017 at 3:33 pm

Contamination of Stethoscopes and Physicians’ Hands After a Physical Examination

Mayo Clinic Proceedings February 2014 V.89 N.2  P.291–299

Yves Longtin, Alexis Schneider, Clément Tschopp, Gesuèle Renzi, Angèle Gayet-Ageron, Jacques Schrenzel, Didier Pittet



To compare the contamination level of physicians’ hands and stethoscopes and to explore the risk of cross-transmission of microorganisms through the use of stethoscopes.

Patients and Methods

We conducted a structured prospective study between January 1, 2009, and May 31, 2009, involving 83 inpatients at a Swiss university teaching hospital. After a standardized physical examination, 4 regions of the physician’s gloved or ungloved dominant hand and 2 sections of the stethoscopes were pressed onto selective and nonselective media; 489 surfaces were sampled. Total aerobic colony counts (ACCs) and total methicillin-resistant Staphylococcus aureus (MRSA) colony-forming unit (CFU) counts were assessed.


Median total ACCs (interquartile range) for fingertips, thenar eminence, hypothenar eminence, hand dorsum, stethoscope diaphragm, and tube were 467, 37, 34, 8, 89, and 18, respectively. The contamination level of the diaphragm was lower than the contamination level of the fingertips (P<.001) but higher than the contamination level of the thenar eminence (P=.004). The MRSA contamination level of the diaphragm was higher than the MRSA contamination level of the thenar eminence (7 CFUs/25 cm2 vs 4 CFUs/25 cm2; P=.004). The correlation analysis for both total ACCs and MRSA CFU counts revealed that the contamination level of the diaphragm was associated with the contamination level of the fingertips (Spearman’s rank correlation coefficient, ρ=0.80; P<.001 and ρ=0.76; P<.001, respectively). Similarly, the contamination level of the stethoscope tube increased with the increase in the contamination level of the fingertips for both total ACCs and MRSA CFU counts (ρ=0.56; P<.001 and ρ=.59; P<.001, respectively).


These results suggest that the contamination level of the stethoscope is substantial after a single physical examination and comparable to the contamination of parts of the physician’s dominant hand.


February 24, 2017 at 3:50 pm

Editorials – Stethoscopes and Health Care–Associated Infection

Mayo Clinic Proceedings March 2014 V.89 N.3 P.277–280

Dennis G. Maki

Divisions of Infectious Disease and Pulmonary/Critical Care Medicine, Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI

Over the past 30 years we have come to fully appreciate the enormous potential for person-to-person spread of virulent nosocomial pathogens (eg, methicillin-resistant Staphylococcus aureus [MRSA], vancomycin-resistant enterococcus [VRE], multidrug-resistant [MDR] gram-negative bacilli and Clostridium difficile, viruses such as influenza A, respiratory syncytial virus, and norovirus, and even Candida species) in the health care setting, with devastating infection being the most feared iatrogenic consequence and one of the greatest threats to hospital safety.

It has long been accepted that the major reservoir of nosocomial infection is infected or colonized patients and the major mode of transmission is the transient carriage of nosocomial pathogens on the hands of noncolonized health care workers having direct physical contact with patients.

Hand hygiene before and after direct patient contact—now most often with a waterless alcohol gel or hand rub—has become an uncompromising expectation for modern-day health care workers …


February 24, 2017 at 3:49 pm

Discontinuation of Contact Precautions for Methicillin-Resistant Staphylococcus aureus: A Randomized Controlled Trial Comparing Passive and Active Screening With Culture and Polymerase Chain Reaction

Clinical Infectious Diseases July 15, 2013 V.57 N.2 P.176-184

Erica S. Shenoy, JiYeon Kim, Eric S. Rosenberg, Jessica A. Cotter, Hang Lee, Rochelle P. Walensky, and David C. Hooper

1Harvard Medical School

2Division of Infectious Diseases, Department of Medicine

3Biostatistics Center

4Center for AIDS Research

5Department of Pathology

6Infection Control Unit, Massachusetts General Hospital, Boston, Massachusetts


There have been no randomized controlled trials comparing active and passive screening for documenting clearance of colonization with methicillin-resistant Staphylococcus aureus (MRSA). We compared the efficacy of active and passive screening using both culture and commercial polymerase chain reaction (PCR) for documentation of MRSA clearance and discontinuation of MRSA contact precautions (CPs).


Inpatients with a history of MRSA infection or colonization enrolled between December 2010 and September 2011 were randomized to either passive (nonintervention arm; n = 202; observation with local standard of care) or active screening (intervention arm; n = 405; study staff screened using culture and commercial PCR). The primary outcome was discontinuation of CPs by trial arm based on 3 negative cultures. In the intervention arm, sensitivity, specificity, and positive and negative predictive values of the first PCR were compared to cultures.


CPs were discontinued significantly more often (rate ratio [RR], 4.1; 95% confidence interval [CI], 2.3%–7.1%) in the intervention arm, including in an intent-to-screen analysis (RR, 2.6; 95% CI, 1.5%–4.7%). The first PCR, compared to 3 cultures, detected MRSA with a sensitivity of 93.9% (95% CI, 85.4%–97.6%), a specificity of 92.0% (95% CI, 85.9%–95.6%), a positive predictive value of 86.1% (95% CI, 75.9%–93.1%), and a negative predictive value of 96.6% (95% CI, 91.6%–99.1%).


Compared to passive screening using culture methods, active screening resulted in discontinuation of MRSA CPs at a significantly higher frequency. Active screening with a single PCR would significantly increase the completion of the screening process. In this randomized controlled trial, active screening was superior to passive screening for discontinuation of contact precautions for methicillin-resistant Staphylococcus aureus, and a single negative nasal swab processed by polymerase chain reaction had a high negative predictive value compared to 3 nasal cultures. Clinical Trials Registration. NCT01234831.


February 19, 2017 at 11:35 am

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